1. Field of the Invention
The subject invention relates to spray nozzles for use in spray drying applications, and more particularly to, spray nozzles of the type which employ locating and/or wear part retention/locking features to facilitate ease of replacement and handling of internal nozzle components and the reinstallation of the assembled unit in the nozzle location.
2. Background of the Related Art
Fluid nozzles or atomizers having a spiral swirl chamber and a spray orifice disposed within a nozzle body have been employed in the past for various applications, including spray drying, aeration, cooling, and fuel injection. U.S. Pat. No. 3,680,793 to Tate, which is herein incorporated by reference in its entirety, discloses a spray nozzle that includes a swirl chamber configured such that the origin of the spiral flow in the swirl chamber and the spray orifice formed in the orifice disc are eccentrically offset relative to each other. The spray orifice and the spiral flow origin were eccentrically offset from each other so as to improve the spray patternation in both large and small spray nozzle applications.
Spray drying is the transformation of a feed liquid from a fluid state into dried particulate form by spraying atomized feed into a gaseous drying medium. The liquid feed can be either a solution, suspension, dispersion, emulsion or slip. Often, the liquid feed contains abrasive solids. The atomization of the feed is accomplished by a spray nozzle. The nozzle must disperse the liquid into small droplets, which should be well distributed into the air stream and also serve as the metering device for the feed system.
In applications such as spray drying, the energy for atomization is supplied solely by the liquid feed pressure with inlet pressures typically exceeding 5,000 psi and occasionally reaching 10,000 psi. Due to the high inlet pressure, the liquid feed passes through the flow passages of the spray nozzle at a high velocity. Liquid feed containing abrasive solids and traveling at a high flow velocity causes erosion of the flow passages in the swirl chamber and orifice disc. As a result, the swirl chamber and orifice disc need to be replaced somewhat routinely.
In most nozzles, replacement of the internal components first requires the removal of the nozzle assembly from the fluid delivery system. Then an adapter which is normally threadably secured to the nozzle body must be disengaged. The adapter functions to secure the internal components, namely the swirl chamber, orifice disc and O-ring seals (adapter and orifice), within the nozzle body. The adapter also facilitates the axial alignment of the swirl chamber by providing a recess for the swirl chamber in its down stream end. Next an adapter seal, which is disposed between the adapter and the swirl chamber is removed. At this point, the remainder of the internal components can be freely removed.
Reassembling the spray nozzle is accomplished by reversing the disassembly procedure. However, difficulty is often encountered when attempting to engage the nozzle body, including the orifice disc and associated O-ring, with the adapter. Generally, the adapter is placed on a flat surface and the orifice disc is placed on top within the alignment recess. The nozzle body with orifice disc disposed therein is also placed on a flat surface with the discharge orifice facing down. In order to assemble the nozzle, either the adapter or the nozzle body have to be inverted. However, when inverting either the nozzle body or the adapter to engage the parts, the internal components unseat, become misaligned and often fall out.
There is a need therefore, for a spray nozzle which facilitates replacement of worn internal components by proving a mechanism for aligning and securing the internal components prior to engagement of the adapter with the nozzle body.